Electric watch



Dec. 27, 1960 P. E. BIEMILLER ET AL 2,966,622

ELECTRIC WATCH Filed Dec. 51, 1956 FIG.6

1NVENTOR9 Phlllp E. Blemiller Marlin S. Wolmer FIG. 2

ATTORNEY United States Patent ELECTRIC WATCH vania Filed Dec. 31, 1956, Ser. No. 631,852

3 Claims. (Cl. 318-128) This invention relates to the means for supplying the motive power to a gear train of an electric watch and includes the electromagnets, the balance wheel and hairs-pring assembly.

In the making of electric wrist Watches having a selfcontained battery and a balance wheel which supplies the motive power to the gear train, two types of construction have been utilized. In the most common of these types a stationary electromagnet having a soft magnetic core is energized and magnetizes a rotor of soft material which is carried by the balance staff. This magnetization of the rotor results in a torque on the balance in one direction, which coupled with the hairspring restoring torque and proper timing of the energization of the electromagnet produces periodic motion of the balance assembly. The other common type of construction utilizes one or more permanent magnets. In this case, the magnetic field from the permanent magnet interacts with the field resulting from the current flowing through a coil. This construction may take either of two forms so long as the coil and the magnets are relatively movable. In one embodiment, the permanent magnets are fixed and the coil is carried by the balance. The configuration is such that when the coil moves into the field of the permanent magnets it is electrically energized, and the interaction of the two magnetic fields produces a torque on the balance. Again, the proper timing of the energization of the coil will result in periodic motion of the balance assembly.

Although satisfactory Watches have been constructed using either soft magnetic material electromagnets or relatively movable permanent magnets and coils, a study of each system reveals that certain defects are inherent. In the electromagnet type, the shape of and the spacing between the rotor and the core piece is quite critical. In addition, the materials for the rotor and the core piece must have consistently low coercive forces so that residual magnetization does not influence the oscillation frequency for various balance amplitudes. These factors coupled with the fact that the efiiciency of such a system is quite low means that a watch constructed on this principle must be extremely delicate. For the permanent magnet type these objections do not apply; however, the presence of permanent magnets in the watch leads to other problems. To have an isochronous balance wheel which is desirable for good timekeeping performance, all balance components must be almost completely non-magnetic. This non-magnetic condition is difiicult to obtain since most commercially available so-called non-magnetic materials are inherently too magnetic for use as balance parts. In addition, the presence of the magnetic field may introduce problems with the behavior of the hairspring. These objections are serious enough to justify the use of some other system.

. This invention attempts to eliminate objections of the type described above and uses both a periodically energized electromagnet for creating a localized momentary 'j magnetic field, and a periodicallyenergized movingcoil adapted to be energized during passage through this momentary magnetic field.

The object of the present invention is to provide an electric impulsing mechanism in which the electrical impulses are used to create magnetic fields, the interaction of the magnetic fields being transferred to oscillatory motion of the balance wheel.

It is a still further object of the present invention to provide a pair of electromagnetic fields which are positioned in the path of movement of an oscillating coil and to energize said electromagnets and said coil simultaneous-ly.

It is a further object of the present invention to provide an electromagnet having a soft magnetic core energized to create electromagnetic fields having opposite flux direction, and to simultaneously energize a coil passing through these fields to establish a magnetic interaction which may be used to produce an oscillatory motion of a balance wheel.

It is a still further object of the present invention to provide a coil carried on an oscillating balance wheel and to establish a pair of electrically energized magnetic fields having opposite flux fiow and to pass said coil through said fields, said simultaneous energization producing a magnetic interaction which results in impulsing the coil and its balance wheel about'its pivots.

The object of the present invention is to provide an electromagnet for creating a momentary magnetic field and a periodically energized moving coil which is adapted to be energized simultaneously with the electromagnet and during the passage of the coil through the momentary magnetic field. i

It is a still further object of the present invention" to provide a pair of localized momentary magnetic fields and to move a coil through said fields so that the coil is simultaneously irnpulsed at two sections during its passage through the momentary field.

It is a still further object of the present invention to provide a pair of stationary momentary magnetic fields of an electromagnet and to electrically energize a moving coil simultaneously with the creation of said pair of magnetic fields, said energization of the coil creating a third magnetic field extending into each of the pair of stationary magnetic fields, the flux of the pair of stationary magnetic fields being in opposite directions and interacting with the flux of the magnetic field of the coil to add on one side of the coil and to oppose on the other side of the coil to produce a resultant force on said coil parallel to the windings of said coil.

It is a still further object to provide an electromagnet having a north and south pole in the same horizontal plane, to maintain a shunt at a fixed distance from said poles and over said poles to provide a magnetic flux path from the north pole of the magnet to the shunt and from the shunt to the south pole of the magnet, and to pass a coil so formed as to have separate sections simultaneously above both north and south poles and to pass an electric current through said coil simultaneously with the energization of the electromagnet, whereby the magnetic flux of the two fields will add on one side of the coil and oppose each other on the other side in each section to provide an impulse parallel to the plane of the coil windings.

It is a still further object of the present invention to provide a shunt partially of magnetic material and partially of non-magnetic material to bridge the poles of an electromagnet, said shunt to be at a fixed distance from said electromagnet leaving sufficient room for the passage of a moving coil between said shunt and said electromagnet.

The invention is illustrated in the accompanying draw; ing in which:

Figure l is a perspective view of that part of an electric watch furnishing the motive power.

Figure 2 is a diagrammatic view of the apparatus shown in Figure 1.

Figure 3 is an electrical schematic diagram as applied to Figure 1.

Figure 4 is a perspective view of the motive power of an electric watch showing a modified form of an electromagnet.

Figure 5 is a diagrammatic view of the apparatus shown in Figure 4.

Figure 6 is an electrical schematic diagram of the figure shown in Figure 4.

Referring to that part of the invention as shown in Figures 1 to 3, a pillar plate '14 of a watch is shown supporting a balance cock 15, a balance wheel 16 having hairspring 17, balance staff 18, upper bearing 19 and regulator 20'. The balance wheel carries a substantially triangular shaped coil 23.

The pillar plate is formed with a pair of parallel slots 24 for the insertion of an electromagnet 25 having enlarged pole tips 26 and 27 forming the north and south poles respectively and secured in position by screws 28. A segment of the pillar plate is removed to provide a wedge shaped depression 29 so that the magnet pole tips 26 and 27 are substantially on the same level as the top of the pillar plate.

A pair of screws 30 locate a shunt having a central portion 34 made of a metal having good magnetic qualities such as annealed low carbon steel and end pieces 35 made of brass or some similar non-magnetic metal. The end pieces are joined to the central portion 34 in any convenient manner and held by screws 36. The shunt is positioned so that the central portion extends over the ends 26 and 27 of the electromagnet and spaced sufliciently therefrom to permit the passage of acoil 23 between the shunt and the ends of the magnet.

The coil 23 is substantially triangular in shape, being formed with an arcuate base and two equal sections which are comprised substantially of straight wires extending in a radial direction from the balance staff. The coil is positioned in the balance wheel which oscillates so that the coil is moved between the shunt and the electromagnet pole tips, the radial sections of the coil passing directly over the tips 26 and 27 of the magnet and spaced so that the straight sections are simultaneously positioned directly over the tips 26 and 27 during the oscillation.

The electrical contact making mechanism which is omitted from Figure l and shown diagrammatically in Figure 3 provides for the energization of the coil and the electromagnet at the instant the radial sections of the coil are directly over the tips 26 and 27 of the electromagnet. By referring particularly to Figure 2 it will be seen, assuming the balance stafi 18 is moving in the direction shown by the arrow, the instant the coil has its radial sides positioned over the tips 26 and 27 of the electromagnet 25, that simultaneous energization of the electromagnet and the moving coil will occur At this time due to energization of the electromagnet, there is a magnetic flux from the north pole 26 of the electromagnet 25 to the induced south pole 38 at the shunt 34.

The magnetic flux continues through the shunt to a north pole 39 induced by the south pole 27 of the electromagnet 25 completing the magnetic circuit. It will thus be seen that a pair of momentary magnetic fields are created between the electromagnet 25 and the shunt 34. The coil 23 during the energization of the electromagnet is positioned so that the radial sections are as shown in Figure 2. At this time the coil is also electrically energized and the magnetic flux due to the current in the coil will follow a circular path shown by the arrow at 40. In a like manner the other side of the coil will provide a circular flux path 41.

The flux path of the electromagnet is shown by the arrows at 43 and 44 being from north to south in each instance. Again referring to Figure 2, it will be seen the the flux 40 and 43 will add on the left side of the coil and oppose on the right side of the coil. In a like manner the flux 41 and 44 will add on the left side of the coil and oppose on the right side of the coil. This will provide a force on the coil which is parallel to the plane of the windings and will provide a magnetic impulse tending to move the coil and the balance in the direction of the arrow. The restoring torque of the hairspring moves the balance in the opposite direction. During this return movement under the torque supplied by the hairspring, neither the electromagnet nor the coil is energized.

An electrical diagram shown in Figure 3 shows a battery 45, a contact making switch 46, a stationary electromagnet 25 and a moving coil 23.

Referring now to the apparatus shown in Figure 4 which is very similar to that in Figure 1, a pillar plate 66 supports a balance cock 61 and a balance wheel and hairspring assembly 62. The pillar plate is formed with a wedge shaped recess 64 having a pair of parallel slots 65 which receive electromagnets 67. Screws 66 hold the electromagnets in place.

The electromagnets have substantially C-shaped cores 68 and 69 respectively with windings 70 and 71 (Figure 5). The windings 70 and 71 are so arranged that the flux fiow of the two magnets is in opposite directions, one of the magnets 67 having its north pole in the lowermost position while the other of the magnets 67 has its south pole in the lowermost position. I

The balance wheel 62 carries a coil 75 identical with the coil 23. The magnets 67 are so positioned with respect to the coil that the radial sections 76 and 77 of the coil are simultaneously positioned between the poles of the two magnets during the oscillating of the balance stall.

Referring to Figure 5, the pair of magnets are shown with the north pole 80 of the left magnet 67 in the lowermost position, while the right magnet 67 has the south pole 81 in its lowermost position. The flow of flux between the magnets being from north to south will produce an upward flow in the left magnet and a downward flow in the right magnet.

Assuming the rotation of the balance wheel 62, as shown by the balance staff 33 in Figure 5, to be in the direction of the arrow 94, the flow of flux in the sections 76 and 77 of the coil will be in a circular direction, as shown by the arrows 92, adding on one side of the coil and opposing on the other side to provide simultaneous impulses on the coil in a direction parallel to the plane on the coil which will impulse the balance wheel in the direction of the arrow 94. Figure 6 shows a battery 90, the necessary switch 91, a pair of electromagnets 67 and 68 and a moving coil 75.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

We claim:

1. In a battery operated electric watch, an oscillating balance wheel, a coil formed with two substantially straight sections and having its windings in the plane of oscillation of said wheel, said coil being carried by said wheel, an electromagnet creating a pair of intensified magnetic fields in the path of oscillation of said coil and having their flux in opposite directions said flux being at right angles to the windings of the coil, and means for simultaneously energizing said coil and said electromagnet so that the magnetic interaction of the intensified magnetic fields with the magnetic field of the coil produces a force on each of the straight sections of said coil, said forces adding to produce an impulse to said balance wheel.

2. In a battery operated electric watch, an oscillating balance wheel, a coil carried by said balance wheel, electromagnetic means establishing intensified electromagnetic fields in the path of movement of said coil, said electromagnetic means having magnetic poles lying in a plane parallel to and closely adjacent the plane of oscillation of said coil, said coil passing through said intensified electromagnetic fields in one position of said coil, and means for simultaneously energizing said electromagnetic means and said coil when said coil is in said one position.

3. In a battery operated electric watch, an oscillating balance wheel, a coil carried by said balance wheel, an electromagnet having a pair of poles terminating in a plane parallel to the plane of oscillation of said balance wheel, said coil having a pair of substantially straight sections positionable above said poles in one position of said coil, a magnetic shunt member stationarily mounted above said balance wheel and overlying said magnetic poles, and means for simultaneously energizing said electromagnet and said coil when said coil is in said one position.

References Cited in the file of this patent UNITED STATES PATENTS 731,857 Chapman June 23, 1903 1,608,786 Fery Nov. 30, 1926 1,911,062 Conrad May 23, 1933 2,495,858 Marti Dec. 30, 1950 2,598,912 Held June 11, 1952 FOREIGN PATENTS 1,118,744 France Mar. 9, 1956 

